I want to bind a gesture in BetterTouchTool to the shut down menu that is invoked by pressing the power button on my MacBook Air.

It's fairly simple to bind gestures to keyboard shortcuts, so what I'm really looking for is a way to bind a keyboard shortcut to the shut down menu. You can't use the power button in BetterTouchTool, so I need to bind it to a standard keyboard shortcut such as Command+Shift+S.